Lift truck



Dec. 14, 1965 H. A. STAMMEN 3,223,267

LIFT TRUCK Filed Sept. 30, 1964 3 Sheets-Sheet 1 JIE. I

INVENTOR. 21420.10 17. 5 MMME/V H/S 4 770 PNEY'S Dec. 14, 1965 A.STAMMEN LIFT TRUCK 5 Sheets-Sheet 2 Filed Sept. 30, 1964 BY W17 Dec. 14,1965 H. A. STAMMEN 3,223,267

LIFT TRUCK Filed Sept. 50, 1964 5 Sheets-Sheet 5 1 IIIIIIIIIIIII I; \u2T INVENTOR. l-l/JEOLD Al. STflHMf/V BY WM;

United States Patent U 3,223,267 LEFT TRUCK Haroid A. Stammen, NewBremen, Ghio, assignor to Qrown Controls (Zorporation, New Bremen, Ohio,a corporation of Ohio Filed Sept. 30, 1964, Ser. No. 434L463 Claims.(Ci. 214-739) This invention relates to a lift truck and moreparticularly to a fork lift truck having pivoted tines. The invention isillustrated herein as adapted to engage and raise baskets of tobaccoleaves. It will be understood, however, that the invention is not solimited.

An object of this invention is to provide a fork lift truck havingpivoted tines of simple and rugged construction.

A further object of this invention is to provide mechanism forautomatically pivoting the fork tines upon initial actuation of powermeans adopted to raise the tines.

Another object of this invention is to provide a latch mechanismpreventing upward movement of the tines until the tines are moved to apredetermined minimum separation one from the other.

Other objects and advantages reside in the construction of parts, thecombination thereof, the method of manufacture and the mode ofoperation, as will become more apparent from the following description.

Referring to the drawings:

FIGURE 1 is a perspective view of a lift truck made in accordance withthis invention as viewed from the front of the truck.

FIGURE 2 is a perspective view of the truck of FIG- URE l, as viewedfrom the front and to one side of the truck.

FIGURE 3 is a perspective view similar to FIGURE 1, but showing parts indifferent positions.

FIGURE 4 is a cross sectional view of a portion of the lift truck asviewed in the direction of arrows 4-4 of FIGURE 3.

FTGURE- 5 is an enlarged elevational view of a portion of the lift truckenclosed within the circle 55 of FIG- URE l and illustrating a latchmechanism.

Referring to the drawings in greater detail, a lift truck made inaccordance with this invention is generally designated 8 and includes abase It) upon which is mounted a housing 12 for the drive and steeringmechanisms. These mechanisms may be entirely conventional and, hence,are not illustrated herein. The lift truck 8 illustrated in the drawingsis intended to employ an electric drive and lift motor (not shown)powered by batteries (not shown) enclosed within battery housings 14located on opposite sides of the housing 12. Projecting forwardly of thebattery housings 14 are elongate, parallel outrigger arms 16 havingsmall wheels 18 at the forward ends thereof. The wheels 13 are used inassociation with caster wheels and a large drive wheel (not shown)located immediately benath the housing 12 and generally centrallythereof to support the entire lift truck. Movement of the truck alongthe floor is controlled by an operator who stands on a platform 2iprovided with a backrest 22 in convenient position to control a steeringhandle 24 connected by a steering column 26 to the steering mechanismlocated within the housing 12. Other suitable control members, such as ahydraulic control lever 28, are located on the top panel of the housing12.

The forward end of the base 19 is recessed to provide a central baseplatform ii. A hydraulic lift cylinder 30 is supported centrally of theplatform 11 upon a support plate 29. The lift cylinder 30 drives apiston 32 having a T-shaped cross head 31 upwardly when fluid issupplied to the cylinder 39 through conduits such as that indicated at33. At the outer ends of the cross head 31 are sprocket wheels 34engaged by lift chains 36. Each of the chains 36 has one end fixed tothe base 10 in any siutable fashion and its other end attached, as by aU-shaped fixture 38 (FIGURE 4) to a rod 46 threadedly engaged in anaperture in a mounting plate 4-1 affixed to a bracket 42, which will bedescribed in greater detail below. Except for the brackets 42, theentire assembly thus far described may be entirely conventional. As willbe appreciated from the ensuing description, initial upward movement ofthe piston 32 upon actuation of the cylinder 30 will cause the ends ofthe chains 36 connected to the brackets 42 to rise. In accordance withthis invention, further upward movement of the piston 32 will cause anentire load engaging or fork lift assembly, generally designated 44, to

rise.

The load engaging assembly 44 comprises a carriage 46 and a tineassembly including the brackets 42 and tines 62 connected thereto. Thecarriage 46 consists of a horizontal top plate 58, a pair of tinesupport plates 43 depending from the rear edge of the top plate 48, ahorizontal lower plate 50, vertical side braces 51 and a vertical centerbraces 52. The braces 51 and 52 are welded or otherwise afiixed to therear edges or surfaces of plates 58, 48 and 50 interconnecting them.Guide rollers 54 mounted on the center braces 52 behind the plates 48and 50 are engaged with the opposed internal faces of a pair of channelmembers 56 which are mounted on the base platform 11 immediatelyforwardly of the housing 12 and on opposite sides of the lift cylinder30. stiffening plates 57 interconnect the channel members 56. As wellknown to those skilled in the art, the guide rollers 54 moving withinthe channels 56 provide for vertical travel of the load engagingassembly 44. The previously mentioned tine support brackets 42 arepivoted upon pivot pins 60 which are supported by the plates 48 andspacer plates 63, there being one pivot pin 60 supported by each pair ofplates 48 and 63.

As may be readily observed from the drawings, each bracket 42 isgenerally L-sh'aped, having an upper horizontal extension 42a to whichthe chains 36 are connected and a vertical extension 421). One tine 62is connected to the lower end of the vertical extension 42b of eachbracket 42. The tines 62 project forwardly or outwardly from thebrackets 42 in generally parallel relationship to the outrigger arms 16.Referring to FIGURE 1, the tines 62 are normally held in spaced apartrelation by pairs of coil springs 64, each connected at one end tofingers 66 which are in turn attached to the horizontal extensions 42aof the brackets 42 and at their other ends to pins 68 affixed to thelower plate 50 by a bracket 70. The coil springs draw the horizontalextensions 42a downwardly against stop plates welded between the bottomedges of the support plates 48 and vertical bracket guide plates 67,extending in front of the brackets 42. While two pairs of coil springs64 are illustrated in FIGURE 1, it will be apparent to those skilled inthe art that only a single coil spring 6 would be necessary and, infact, other biasing devices such as a pneumatic cylinder could be usedin place thereof.

Also shown in FIGURE 1 is a basket or tray 72 of the type commonly usedto support a pile of tobacco leaves. The tines 62 are wedge or chiselshaped for the purpose of sliding partially underneath the upwardlyturned ends of the basket 72. Also, the leading and inner edges 62a ofthe tines 62 slope rearwardly to avoid damage to the baskets 72 as thetines 62 advance toward the basket 72.

The operation of the device as thus far described is as follows. Uponinitial upward movement of the piston 32, the brackets 42 are pivotedabout the pivot pins 66 against the bias of the springs 64, so as todraw the inner ends of the horizontal extension 42a upwardly, whereuponthe tines 62 are pivoted one toward the other, thereby wedging orcamrning underneath the basket or tray 7 2. This movement of the tines62 continues until the upper surfaces of the brackets 42 engage thelower surfaces of a pair of stop screws 74 threaded through apertures inthe top plate 58. Following this initial movement of the cylinder 30,the tines 62 are in generally parallel relationship but remain adjacentfloor level between the outrigger arms 16, as illustrated in FIGURE 2.Because the upper edges of the brackets 42 are engaged with the lowersurfaces of the stop screws 74, continued upward movement of the piston32 causes the lift assembly 44 to rise into that position shown inFIGURE 3.

The load is lowered by returning the piston 32 downwardly into thecylinder 30. During lowering, the weight of the load and the carriage 46maintains the springs 64 taut and the upper surfaces of the brackets 42remain engaged with the stop screws 74. Subsequently, the carriage 46lowers to a fixed stop created by engagement of the bottom edges of thebraces 52 with the base platform 11. Because the load is thereafterelfectively supported by the base platform 11, the springs 64 return totheir original position as shown in FIGURE 1 while the piston 32continues to lower.

The afore described apparatus is ideally suited for use in tobaccowarehouses. Several hundred pounds of tobacco leaves may be loaded onbaskets such as that illustrated at 72. The tobacco leaves overhang theedges of the basket. Therefore, the operator cannot see the pickuppoints. By straddling the basket, however, and moving the forked tines62 symmetrically toward one another near floor level, the basket caneasily be engaged for pickup. It will be appreciated that the hydrauliccontrol system for the cylinder 32 can be entirely conventional and neednot be different from any other control system used merely to raise thepiston 32. Thus, separate controls for moving the tines 62 relative toone another are unnecessary. A single control button, which may belocated on the steering handle 24, used to actuate the hydraulic pumpwhich supplies fluid to the cylinder 32 is all that is required to firstpivot the tines 62 one toward the other, subsequently raise the tines 62above floor level, return the tines 62 to floor level and separate thetines.

The top of the stack of tobacco leaves in basket 72 may be engaged by astabilizer assembly comprising a pair of spaced generally L-shaped arms80, the upper ends of which are connected by three stiffening braces 82and which overlie the tobacco leaves. The vertical portions of the arms80 are adapted to slide in sleeves 84 attached to opposite sides of thehousing 12. The vertical height of the arms 80 can be adjusted byremoval and reinsertion of lock pins 86 which pass through apertures inthe upper ends of the sleeves 8 and through apertures 88 in the arms 80.I

For some uses it may be desirable or even essential that a predeterminedminimum separation of the tines 62 is reached prior to the raising ofthe lift assembly 44. To this end, a latch assembly, shown best inFIGURE 5, may be provided for preventing vertical upward movement of thelift assembly 44 relative to the base 10. The latch assembly may includea latch bar 92 mounted for horizontal sliding movement on a bracket 92supported by the base 10. A coil spring 94 having one end attached to apin 96 affixed to the bracket 92 and its other end affixed to a pin 98connected to the latch bar 90 biases the latch bar to the right, asviewed in FIGURE 5, toward the adjacent brace 52. A latch roller 100 isattached to the brace 52 as by a bracket 102 and rolls upon a pin 194which passes through the bracket 102 and an aperture in the lower plate50. See FIGURE 3 in addition to FIG- URE 5. When the parts are in theposition shown in full lines in FIGURE 5, which is the same as thatshown in FIGURE 1, and the tines 62 positioned as shown in FIGURE 1,upward movement of the lift assembly 44 is prevented, since the loweredge of the latch bar 9% prevents the latch roller 1% from movingupwardly. The usual hydraulic overload protection system or by-passcircuit associated with the lift cylinder 39 will go into operationshould further movement of the tines 62 toward one another be prevented.If the tines 62 are pivoted toward one another, however, a lug or plate106 connected to the rear face of the vertical extension 42b of thebracket 42 engages the end face of a latch release bar 108 which passesthrough a sleeve 110 and has an enlarged end section 112 abuttingagainst the face of the latch bar 92 closest to the brace 52. Asapparent from an inspection of FIGURE 5, movement of the tine 62illustrated therein to the left causes the release bar 198 to be movedto the left; consequently, the latch bar is also moved to the leftwhereby vertical upward movement of the latch roller 3% to the positionindicated by phantom lines a is permitted. A light spring a housedwithin the sleeve I10 biases the release bar 198 to the right duringvertical travel of the lift assembly 44. As the lift assembly 44 islowered so as to return the tine 62 to adjacent ground level, the roller1% first engages a sloping end surface of the latch bar 9%, thus cammingit against the bias of the spring 94 whereupon the latch roller 1%returns to its initial position beneath the latch bar 90 illustrated inFIG- URE 5. The enlarged end 112 of the release bar 108 engages the endface of the latch bar 90 before the roller I60 becames disengagedtherefrom, and it also returns to the full line position shown in FIGURE5. Thus, it may be seen that the latch mechanism is automatically resetas the lift assembly 44 lowers to return the tines 62 to ground level.Subsequent upward movement of the lift assembly 44 is prevented untilthe bracket 42 is returned to a position such as that indicated by thephantom lines 420 in FIGURE 5. The latch assembly illustrated in FIGURE5 is shown in connection with the bracket 42 and tine 62 on the rightside of the lift truck as viewed in FIGURE 3. If desired, an identicallatch assembly responsive to the position of the tine 62 on the leftside as viewed in FIGURE 3 could also be mounted on the base platform 11and carriage 46.

Although the preferred embodiment of the device has been described, itwill be understood that within the purview of this invention variouschanges may be made in the form, details, proportion .and arrangement ofparts, the combination thereof and mode of operation, which generallystated consist in a device capable of carrying out the objects setforth, as disclosed and defined in the appended claims.

Having thus described my invention, I claim:

1. In a lift truck, the combination comprising: a base, a carriagemounted for vertical movement relative to said base, a pair of bracketsmounted on said carriage for pivotal movement about generally parallel,horizontal axes, a pair of load engaging tines, one connected to eachbracket and movable therewith, power operated lift means mounted on saidbase and connected to said brackets pivoting said brackets about saidaxes, and a stop surface fixed relative to said carriage preventingpivotal movement of said tines and said brackets beyond a predeterminedposition, said tines pivoting about said axes upon initial operation ofsaid lift means and said carriage raising upon continued operation ofsaid lift means.

2. The combination of claim ll, further including a slidable latch barmounted on said base, a latch element mounted on said carriage, biasmeans normally positioning said latch bar in overlying relationship tosaid latch element whereby upward movement of said carriage isprevented, a latch release means engaged with said latch bar responsiveto pivotal movement of one of said tines and moving said latch bar awayfrom overlying relationship to said latch element when said one of saidtines is pivoted to a predetermined position.

3. In a lift truck, the combination comprising: a base, a carriagemounted for vertical movement relative to said base, a pair of loadengaging tine assemblies pivotally connected to said carriage,releasable latch means interconnecting said carriage and said basenormally preventing vertical travel of said carriage, and latch rel-easemeans operatively engaged by one of said tine assemblies during pivotalmovement thereof to release said latch means.

4. In a lift truck of the type having a vertically driven lift piston, afork lift assembly comprising; a carriage mounted for vertical movementon said truck, a pair of tine assemblies mounted for pivotal movement onsaid carriage, stop means on said carriage engaged by said tineassemblies in a predetermined position of said tine assemblies, and biasmeans connected to said carriage and said tine assemblies biasing saidtine assemblies away from said stop means, said tine assemblies beingconnected to said driven lift piston and pivoting against said biasmeans upon upward movement of said piston into engagement with said stopmeans.

5. In a lift truck of the type having a vertically driven lift piston, afolk lift assembly including: a carriage mounted for vertical movementon said truck, a time assembly mounted for pivotal movement on saidcarriage and connected to said lift piston, stop means on said carriageengaged by said tine assembly in a predetermined pivotal positionthereof, and bias means connected to said tine assembly biasing saidassembly away from said stop means, upward movement of said lift pistonpivoting said tine assembly toward said stop means against said stopmeans and raising said carriage after said tine assembly engages saidstep means.

No references cited.

HUGO 0. SCHULZ, Primary Examiner.

1. IN A LIFT TRUCK, THE COMBINATION COMPRISING: A BASE A CARRIAGEMOUNTED FOR VERTICAL MOVEMENT REALTIVE TO SAID BASE, A PAIR OF BRACKETSMOUNTED ON SAID CARRIAGE FOR PIVOTAL MOVEMENT ABOUT GENERALLY PARALLEL,HORIZONTAL AXES, A PAIR OF LOAD ENGAGING TINES, ONE CONNECTED TO EACHBRACKET AND MOVABLE THEREWITH, POWER OPERATED LIFT MEANS MOUNTED ON SAIDBASE AND CONNECTED TO SAID BRACKETS PIVOTING SAID BRACKETS ABOUT SAIDAXES, AND A STOP SURFACE FIXED RELATIVE TO SAID CARRIAGE PREVENTINGPIVOTAL MOVEMENT